When used properly, the simple answer is no. However, like most other things in this world, epoxy could be harmful if used improperly. For one thing, it often gives off some harsh fumes as it dries. These fumes are the volatile chemicals in which the epoxy is suspended, so you don’t want to breathe them. Not only that, but you don’t want to get this stuff on your hands. It is very hard to remove, so you should wash your hands with a solvent solution quickly.
Finally, we should mention the fact that epoxy produces heat. When its two components are mixed, a chemical reaction occurs, and this reaction is exothermic. That’s a fancy way of saying that heat is produced as a by-product of the reaction. So, you need to make sure you don’t mix them in a cup made of paper or thin plastic. They could even catch fire in some cases, so make sure you use a mixing container that can handle the heat.